We allready have a table to store all available IM services, acs-admins are able to de/activate singel IM Services.
The jabber package is not able to handel more then one screen for a Service and User.
I'm not sure if this is neccessary , I think it may be more usefull to let a user have more than one Identity under wich he can handel a set of screens (one for each IM Service).
This way the contacts of a user get better organized, all conntacts he adds to his 'Work' identity will be displayed under this Identity don't matter from wich IM System they are. If he has a second screen (for privat use) in any IM Service, he can create a new 'Privat' Identity, and use the screen with this Identity.